<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>盒模型</title>
    <style>
        /* css reset */
        *{
            margin: 0;
            padding: 0;

        }
        header,footer{
            height: 44px;
            background-color: #969696;
            text-align: center;

        }
        body{
            display: flex;
            flex-direction: column;
            height: 100vh;
        }
        
        .box{
            /* 
            display 可以去切换盒子的能力; 
            box-sizing 可以去设定盒子的计算方案
            默认值是content-box
            当指定宽度和高度的时候 指定的是 内容的大小 这是标准盒子模型
            当是border-box的时候 则包含边框和内边距的大小 这是IE盒子模型

            */
            /* box-sizing: border-box; */
            width: 200px;
            height: 200px;
            background-color: #588140;
            margin: 10px;
            padding: 5px;
            border: 2px solid #000;
        }
        .flex{
            display: flex;

        }
        main{
            flex:1;
            position:relative;

        }
        .inner{
            position: absolute; 
            top: 0;
            left: 0;
            width: 100px;
            height: 100px;
            background-color: pink;
            border-radius: 50%;
        }
        .container{
            flex:1;
            overflow: scroll;
        }
        footer{
            display: flex;
            align-items: center;
            justify-content: center;
        }
        .more{
            position: absolute;
            width: 50px;
            height: 50px;
            background-color: yellow;
            top: 50%;
            left: 50%;
            /* transform: translate(-50%,-50%); */
            margin-left: -25px;
            margin-top: -25px;
        }
    </style>
</head>
<body>
    <header>
        <h1>标题</h1>
    </header>
    <div class="container">
        <div class="row flex">
            <aside class="box">
                box1
            </aside>
            <main class="box">
                <div class="inner" style="z-index: 999;">

                </div>
                <div style="position: absolute; width: 100px;;height: 100px;background:black">
                    123
                </div>
                <div style=" width: 100px;;height: 100px;background:rgb(255, 255, 255)">
                    123
                </div>
            </main>
            <aside class="box">
                box3
            </aside>
        </div>
        <div class="row flex">
            <aside class="box">
                box1
            </aside>
            <main class="box">
                <div class="inner">

                </div>
                <div style="width: 100px;;height: 100px;background:black">
                    123
                </div>
                <div style="width: 100px;;height: 100px;background:rgb(255, 255, 255)">
                    123
                </div>
            </main>
            <aside class="box">
                box3
            </aside>
        </div>
        <div class="row flex">
            <aside class="box">
                box1
            </aside>
            <main class="box">
                <div class="inner">

                </div>
                <div style="width: 100px;;height: 100px;background:black">
                    123
                </div>
                <div style="width: 100px;;height: 100px;background:rgb(255, 255, 255)">
                    123
                </div>
            </main>
            <aside class="box">
                box3
            </aside>
        </div>
        <div class="row flex">
            <aside class="box">
                box1
            </aside>
            <main class="box">
                <div class="inner">

                </div>
                <div style="width: 100px;;height: 100px;background:black">
                    123
                </div>
                <div style="width: 100px;;height: 100px;background:rgb(255, 255, 255)">
                    123
                </div>
            </main>
            <aside class="box">
                box3
            </aside>
        </div>
    </div>
    <footer>
        <p>111111111</p>
    </footer>
    <div class="more">
        2222
    </div>
</body>
</html>